title: The effect of radiation quality on genomic DNA methylation profiles in irradiated human cell lines.
abstract: It has been acknowledged for many years that radiation exposure induces delayed, non-targeted effects in the progeny of the irradiated cell. Evidence is beginning to demonstrate that among these delayed effects of radiation are epigenetic aberrations, including altered DNA methylation. To test the hypothesis that differences in radiation quality affect radiation-induced DNA methylation profiles, normal AG01522 and RKO colon carcinoma cells were exposed to low-LET X rays and protons or high-LET iron ions. DNA methylation was then evaluated at delayed times using assays for p16 and MGMT promoter, LINE-1 and alu repeat element, and global methylation. The results of these experiments demonstrated radiation-induced changes in repeat element and global DNA methylation patterns at ∼20 population doublings postirradiation. Further, radiation-induced changes in repeat element and global DNA methylation were more similar between proton- and iron-ion-irradiated cells than X-irradiated cells, suggesting that radiation quality rather than LET alone affects the radiation-induced epigenetic profile. Since alterations in DNA methylation have also emerged as one of the most consistent molecular alterations in cancer, these data also suggest the possibility that radiation-induced carcinogenic risk might be affected by radiation quality.
authors.affiliation: Department of Radiation Oncology, Radiation Oncology Research Laboratory, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Wilfried
authors.initials: W
authors.lastname: Goetz
authors.forename: Michelle N M
authors.initials: MN
authors.lastname: Morgan
authors.forename: Janet E
authors.initials: JE
authors.lastname: Baulch
mesh_terms: D020087:Alu Elements / Q000235:genetics; D016923:Cell Death / Q000528:radiation effects; D045744:Cell Line, Tumor; D004249:DNA Damage; D019175:DNA Methylation / Q000528:radiation effects*; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D005720:Gamma Rays; D019942:Genes, p16; D015894:Genome, Human / Q000235:genetics*; D006801:Humans; D007501:Iron; D018499:Linear Energy Transfer; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D011522:Protons; D025521:Tumor Suppressor Proteins / Q000235:genetics; D014965:X-Rays
chemical_list: D011522:Protons; D025521:Tumor Suppressor Proteins; D007501:Iron; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes